Engine starter



L L E E A R ENGINE STARTER Original Filed Dec.

INVENTOR 'RoLLm I ABELL H45 ATTORNEY Patented Mar. 19, 1929.

ROLLIN ABELL, OF MILTON, MASSACHUSETTS.

ENGINE STARTER.

Application filed December 14, 1923, Serial No. 680,681. Renewed. rch 2,1928.

This invention relates to automatic starters for internal combustionengines, and its object is to provide an improved construction and toovercome various faults that exist in the constructions hitherto in use.

For example, one such fault is that when the teeth of the axiallymovable pinion strike the ends of the teeth of the engine gear one ormore teeth become chipped in consequence of failure to mesh properlybefore the starting torque is applied, and in time the pinion'or enginegear or both become so badly mutilated that the mechanism can no longerfunction.

Again, sometimes the engine backfires when started, and when this occursthe starting mechanism sustains a tremendous reaction which, in manycases, bends or even breaks the shaft of the starting motor, While inother cases it breaks other parts of the starting mechanism or sotightens them that they will not release.

Former constructions also sustain breakage or cause burning out of thestarting motor in consequence of accidentally turning on the startingcurrent while the traction wheels are geared and clutched to the engine,and sustain breakage when the starting current is turned on while theengine is running.

In view of these and other causes of trouble the object of the presentinvention is to provide a starting mechanism that will Withstand allpossible conditions of use and misuse without damage to itself, thestarting motor or other parts of a power organization. In

other words, the object isto provide a foolproof starting mechanism.

More specifically, .an object of the invention is to provide, in astarting mechanism of the character mentioned, improved means forautomatically releasing the axially movable pinion from its source ofrotation when its axial movement is arrested by the ends of the teeth ofthe engine gear, so that it may turn backward, if necessary, far enoughto slip into gear before the starting torque is applied to it.

Another object is to provide for relief of the starting mechanism, andparticularly of the starting motor, from excessive counter torqueso thatno damage or undue strains will be sustained when the engine backfires.

A-feature of the invention consists in an axially movable transmissionunit including an, initially coupled toothed clutch arranged to beuncoupled by stoppage of the axial move- 5 ends of the teeth of thepinion clash with those 30 of the engine gear in such a way as to arrestthe axial movement of the inion the latter is released from the source 0starting torque so that instead of causing mutilation of the teeth itmay turn in whicheverdirection the teeth 5 tend to deflect it and gointo gear before the starting torque is applied.

Another feature consists in a transmission unit having automaticreleasing means to rehave said unit and the starting motor fromexcessive torque, as, for example, when the engine is restrained againstturning over or when it backfires while the starting pinion and enginegear are in mesh. The said releasing means and the aforesaid clutch maybe, and

preferably are, combined one in the other to make the mechanism simple,compact and efficient. Furthermore, Whenfso combined, a single springmay be utilized both for relieving counter-torque and for automaticallyso resetting or recoupling the clutch after the latter has beenuncoupled.

A toothed clutch of the type shown, having beveled or rounded teeth, hasproved to be extremely satisfactory under all conditions of 5 use andmisuse, since it does not become heated or stick from any cause evenwhen subjected repeatedly to the harshest tests that could be imposedupon it. Furthemore, it is selfcleaning and not affected peceptibly byoil or dirt, though it works better and Wears longer if lubricated. Inany event, the teeth insure a positive driving connection irrespectiveof dirt and oil, except when the torque is developed to a predetermineddegree at which the clutch automatically releases.

Other features of the invention are hereinafter described and claimed,and are illustrated by the drawings. Referring to the latter,

Figure 1 is a side elevation of a starter mechanism embodying theinvention;

Fig. 2 is an end elevation thereof;

Fig. 3 is a longitudinal section;

Fig. 4 is a perspective view of one of the clutch members; and

Fig. 5 is a development of the cam by which the starting pinion isshifted to its Working position,

a portion of astarting motor and a portlon of an engine gear 11 havingspur teeth.

This gear is usually formed on or fastened to the fly-wheel of theinternal combustion engine.- The starting shaft 12 forms a part of therotor of the starting motor and is 'ournaled in the casing of thelatter. An outoard bearing (not shown) would preferably be provided tosupport the shaft near the gear 11.

A hardened steel sleeve 13 is fixed to the shaft by a key 14 andset-screw 15, and is formed with two integral and diametrically oppositecylindric lugs 16. This sleeve and the shaft 12 provide what ishereinafter termed a rotary operating'unit.

A spur pinion 17, hereinafter termed the starting pinion, is provided toturn the engine gear 11 and is shifted'axially to and from the latter bya transmission unit which includes a c vlindric hardened steel sleeve 18and a clutch member 20 of smaller diameter than the pinion to clear theengine gear 11.

The sleeve 18 is arranged toslide axially on the shaft 12 and is free toturn relatively to the shaft within certain limits. Also. the pinion,which has a cylindric bore .to fit the sleeve 18, is arranged to slideaxially thereon and turn relatively thereto. The sleeves 13 and 18 areformed to be assembled in nested relation, the sleeve 18, as shown,being provided at one end with a barrel portion 19 to receive the sleeve13. Twin cam slots 21. each double-acting, are formed in the barrelportion 19 to cooperate with the lugs 16. The internal diameter of theportion 19 is preferably larger than the sleeve 13 to provide clearance.This feature avoids the necessity of smoothing and truing the internalsurface of the portion 19 and the periphery of the sleeve 13, andprevents sticking of the parts even when they are coated with heavylubricating oil in cold weather.

The cam-sl0ts 21 are open at the right hand end of the portion 19 toadmit the lugs 16 so that the parts 13 and 19 may be assembled, and whenthe lugs have been placed in the slots the two sleeves may be kept innested relation by springing an expansible locking ring 22 into a groove23 5) in the periphery of the portion 19. Moreover, the slots 21 are soshaped near their open ends that the lugs can .not run out in operationeven if the ring 22 is omitted. In fact, the lugs never advance so faras to touch the ring, since the steep surfaces 29 limit the extent towhich the lugs may advance toward the open ends of the slots. As shown,the slots 21 are curved to provide gradually increasing pitch from theirclosed ends to and including the steep portions 29 which, beinghookshaped, prevent the lugs from advancing so far as to touch thering22.

The outboard or front end of the sleeve 18 and the clutch member 20,which is in the form of a collar, have cooperative screwthreads 24 toprovide arigid connection. Before the clutch collar 20 is screwed on,the starting pinion 17 is slipped on the sleeve; then the clutch collaris screwed on as far as it will go.

The front or entering end of the starting pmlon and the confronting endof the collar 20 are provided with cooperative clutch formations bywhich rotation is transmitted from one to the other. The illustratedclutch formations comprise teeth 25 on the pinion and teeth 26 on thecollar. These teeth project axially and are preferably rounded orotherwise beveled to effect declutching when the torque is developed toa predetermined degree. As shown, the clutch teeth of the pinion projectaxially from the hub thereof and merge with the spur teeth respectively,and the front or leading ends of the spur teeth are preferably roundedor beveled to facilitate their entrance between the teeth of the enginegear 11.

Any suitable yielding means may be provided to keep the clutch membersnormally in cooperative relation, but I prefer for this purpose acompression spring 28 surrounding and carried by the sleeve 18 and heldunder initial compression. As shown, the spring is seated against theforward end of the portion 19 and the rear end of the pin ion. Theapplied force of the spring is slightly more than enough'to preventdeclutching under the average torque required to turn the engine gear 11when conditions are normal, but at the same time limited to permitgreater torque of predetermined degree to efiect declutching rather thanto impose injurious stresses on the mechanism.

Figs. 1 and 3 show the transmission unit in its initial position. thepinion 17 being out of gear but clutched to the collar 20. Upon givingcurrent to the starting motor the shaft 12 turns in the directionindicated by the arrow in Fig. 1. As the lugs 16 act on the cam surfacesthe transmission unit is shifted axially, and, if the teeth of thepinion 17 enter readily between the teeth of the engine gear the pinionremains clutched. WVh'en the lugs 16 engage the steep portions 29 of thecams the axial thrust becomes negligible but the maximum torque isdeveloped and the transmission unit is rotated positively. If the engineis free, that is, not clutched-or geared to the wheels, and not stuck inits bearings, it will be turned over and started without causingdeclutching of the pinion 17, but if, for any reason, the engine doesnot respond to the starting torque it will not arrest the shaft 12because, under these conditions, the clutch teeth 25, 26 will permit,and

will be declutched by, relative rotation of the transmission unit andthepinion while the latter remains stationary and in gear.

This relieves the mechanism and the starting motor from excessive torqueand avoids burning out the motor.

Sometimes the teeth of the pinion 17, instead of going readily into gearas above suggested, abut the teeth of the engine gear, and inconsequence the pinion is arrested. Here, instead of breaking one ormore teeth, the transmission unit, by its continued axial movement,declutches itself from the arrested pinion while the spring 28 yields.Thus, the pinion is uncoupled from its source of rotation and relievedfrom all torque. Being now free to turn in either direction and stillunder axial thrust of the spring, the pinion teeth slip between theteeth of the engine gear and immediately the pinion is automaticallyre-clutched to the transmission unit.

7 Then the starter functions just as though no arrestof the pinion hadoccurred.

\Vhen the engine starts to run on its own power it drives the pinion ata faster speed than that caused by the starting motor, and the camsurfaces of the element 19 then react on the lugs 16, with the resultthat the transmission unit is returned to its initial position with thepinion out of gear.

- Let it now be assumed that the engine backfires while the startingmeehanismis in gear and operating under the power of the starting motor.\Vith former types of starting mechanism this might force the pinionlaterally and bend or break the shaft 12, break teeth from the gear 11or the starting pinion, split the casing of the starting motor, or causesome other but equally serious damage. But with my improved constructionthe reaction )IOdllCGd by backfiring merely causes declutcliing of thepinion from the transmission unit because the teeth 25, 26 do notmaintain positive connection when they force themselves apart. They arerounded or otherwise beveled enough tOa force themselves apart underconditions of abnormal resist ance or reaction, and at all. times theyconstitute a safeguard against the development of torque above apredetermined degree. This, of course, is dependent upon two factors,viz, the shape of the clutch teeth and the strength of the spring 28.Thus. even though the pinion is locked against all rotation or turnedreverscly by the engine gear, the starting motor may continue to takecurrent without danger of burning out and may continue to turn the shaft12 without doing any harm. The only result will be that the clutch teethof the collar 20 will click over those of the pinion.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. An engine starter comprising a rotary operating unit and atransmission unit having cooperative portions by which said transmissionunit is shifted axially and rotated, a

starting pinion arranged to be shifted axially by said transmissionunit, said pinion and said transmission unit having cooperative clutchteeth,'and a spring arranged to maintain said pinion and saidtransmission unit normally in clutched relation, said clutch teeth beingformed to effect relative axial movement and declutching. of said pinionand said transmission unit with a starting torque of predetermineddegree but to maintain a substantially positive driving connection withstarting torques of lesser degree.

2. An engine starter comprising a rotary operating unit and atransmission unit having cooperative portions by which said.transmlssion unit is shifted axially and rotated, said transmission unithaving a toothed clutch portion and having a cylindric sleeve portionbetween said clutch portion and said operating unit. a starting pinionarranged to slide axially on said cylindrie portion and having a toothedclutch portion arranged to cooperate with that of said transmission unitto form a driving connection, and a spring arranged to maintain saidpinion and said transmission unit normally in clutched relation, saidclutch portions being formed to force themselves apart by relativerotation under torque of a predetermined degree.

3. An engine starter comprising a rotary operating unit and atransmission unit having cooperative portions by which said tansmissionunit is shifted axially and rotated. a starting pinion rotatablerelatively to said transmission unit and arranged to be shifted axiallythereby. said pinion having clutch teeth at one end of its lmb and saidtransmission unit having beveled clutch teeth arranged to engage saidteeth of said pinion to form a driving connection, and a spring arrangedto maintain said pinion and said transmission unit normally in, clutchedrelation.

4. In an engine starter of the type in which a rotary transmissionunit-is shifted axially and driven by a rotary operating unit, thecombination with said transmission unit of a clutch member afiixedthereto, a relatively rotatable and axially movable starting pinion'arried thereby, and a spring arranged to keep said pinion normallyagainst said clutch member, said pinion and said clutch member havingcooperative clutch teeth the driving faces of which are beveled torupture the starting connection when the starting torque is developed toa predetermined degree.

5. In an engine starter of the type in which a rotary transmission unitis shifted axially by a rotary operating unit, the, combination withsaid transmission unit, of a relatively rotatable starting pinioncarried thereby, a clutch member fixed to said transmission unit, saidclutch member and one end of said pinion having cooperative clutch teethformed to repel the pinion axially and declutch the latter underabnormal torque, and a spring arranged to return said pinion toclutching position.

6. An engine starter comprising a rotary operating unit, a transmissionunit arranged to be shifted axially and rotated thereby, saidtransmission unit having a cylindric portion, --a starting pinion havinga cylindric bore arranged on said portion, said transmission unit andsaid pinion being relatively rotatable and axially movable, thefront endof said pinion having an axially projecting clutch formation, meansfixed to said trans mission unit and having a complemental clutchformation to cooperate with that of said pinion, and a spring arrangedto keep said pinion normally in clutched relation to said means.

7. An engine starter comprising a transmission unit, a rotary operatingunit arranged to impart axialmovement and rotation to said transmissionunit, a starting pinion carried by said transmission unit, said pinionand transmission unit being relatively rotatable and relatively movableaxially, the front end of said pinion having clutch teeth, a clutchelement fixed to said transmission unit. and having clutch teeth tocooperate with said clutch teeth, and a spring arranged to keep saidpinion normally in cooperative relation to said clutch element, thedriving faces of said clutch teeth being beveled to effect relativedeclutching movement when the starting movement of the pinion isprevent-ed or arrested.

8. An engine starter comprising a transmission unit, a rotary operatingunit arranged to impart axial movement and rotation to said transmissionunit, a starting pinion carried by said transmission unit, saidpinionand transmission unit being relatively rotatable and relatively movableaxially, the front end of said pinion having clutch teeth, a clutchelement fixed to said transmission unit to cooperate with said clutchteeth, and a spring arranged to keep said pinion normally in cooperativerelation to said clutch element, said clutch teeth and said clutchelementbeing formed to effect declutching of the pinion under excessivetorque to relieve the torque.

9. An engine starter comprising a transmission unit, a rotary operatingunit arranged to impart axial movement and rota tion to saidtransmission unit. a starting pinion carried by said transmission unit,said pinion and transmission unit being relatively rotatable andrelatively movable axially, a collar fixed to said transmission unit toengage the front end of said pinion, and a spring arranged to keep saidpinion normal ly against said collar, said pinion and said collar havingcooperative clutch teeth to 1'0- tate the pinion under, normaltorque-load, said teeth being formed to repel and declutch the pinionunder an excessive torque-load so that the transmission unit may rotatewithout rotating the pinion.

10; An engine starter comprising a transmission unit, a rotary operatingunit arranged to impart axial movement and rotation to said transmissionunit, a starting pinion carried by said transmisison unit, said pinionand transmission unit being relatively rotatable and relatively movableaxially, said pinion having spur teeth for meshing with a gear of theengine and having clutch teeth at its front end projecting axially fromits hub, a clutch element of smaller diameter than said spur teeth fixedto said transmission unit to cooperate with said clutch teeth of thepinion, and a spring arranged to keep said pinion normally in clutchingrelation to said clutch element.

11. An engine starter comprising a cylindric operating shaft, aninternally and externally cylindric sleeve arranged to slide axially andturn on said shaft, means fixed to said shaft to shift said sleeveaxially and transmit rotation thereto, a starting pinion having acylindric bore coextensive with its length arranged to slide axially andturn on said sleeve, a collar secured on said sleeve to retain saidpinion, and a compression spring surrounding said sleeve and arranged tokeep said pinion normally pressed against said collar, said pinion andsaid collar having cooperative external clutching portions to transmitrotation to said pinion, which clutching portions are formed to bedeclutched by their reaction with starting torque of a predetermineddegree.

12. An engine-starter comprising a rotary operating shaft, a drivingsleeve aflixed thereto, and a driven sleeve provided with a startingpinion arranged to slide axially on said shaft, one end of one of saidsleeves being nested in the other one of said sleeves, one of saidsleeves being provided with a cylindric operating lug and the otherbeing formed with a cam slot in which said lug operates, said slot beingopen at one end to permit assembling said sleeves but being shaped nearsaid end to prevent said lug from running out in operation.

13. An engine-starter comprising a rotary operating shaft, a drivingsleeve afiixed thereto, and a driven sleeve provided with a startingpinion arranged to slide axially on said shaft. one end of one of saidsleeves being nested in the other one of said sleeves, one of saidsleeves being provided with a cylindric operating lug and the otherbeing formed with a cam slot in which said lug operates, said slot beingopen at one end to permit assembling said sleeves and having a hookshapeat said end to prevent said lug from runningout in operation- 14. Anengine-starter comprising a rotary operating unit and a transmissionunit arranged in coaxial relation and provided one with a radial lug andthe other with a doubleacting cam slot to cooperatewith said lug, saidcam slot being open at one end to provide for assembling saidunits andhavinga steep portion near said open end to prevent p the lug fromrunning out in operation, and

said transmission unit being provided with a starting pinion. I 1 Intestimony whereof I have afiixed my signature thisfifth day of December,1923.

ROLLIN ABELL

